Efficacy and Safety of Single Microneedle Radiofrequency vs. Photodynamic Therapy on Moderate-to-Severe Acne Vulgaris: A Prospective, Randomized, Controlled Study
Acne vulgaris is a common skin disorder that significantly impacts both physical and psychosocial health. While photodynamic therapy (PDT) has been used to treat moderate-to-severe acne, its adverse reactions have prompted the search for alternative treatments with fewer side effects. Recently, radiofrequency has emerged as a promising option for moderate acne. This study aimed to evaluate the efficacy and safety of single microneedle radiofrequency (MRF) compared to PDT in treating moderate-to-severe acne vulgaris through a prospective, randomized, controlled trial.
The study was approved by the Institutional Review Board and the Ethics Committee of Xiangya Hospital of Central South University and was registered in the Chinese Clinical Trial Registry. Written informed consent was obtained from all participants. The sample size calculation ensured at least 80% power and a significance level of 0.05. To detect a clinically important mean difference of 30% between the two groups, at least 36 patients per group were required. To account for potential withdrawals, 80 patients with Fitzpatrick skin types III to IV and moderate-to-severe acne (Investigator Global Assessment [IGA] scale of 3 or 4) were enrolled. Exclusion criteria included a history of photosensitive disorders, use of certain medications, recent facial procedures, and pregnancy or lactation in female subjects. Participants were instructed to avoid any anti-acne treatments except for standard washing and moisturizing procedures during the study.
Participants were randomly allocated to either the PDT or MRF group using a random number table generated by SPSS version 19.0. Treatment allocation was concealed in an opaque envelope and revealed to the clinician on the day of the first treatment. In the MRF group, patients were positioned supine, and a 3.5-mm-long needle was inserted into the lesional follicular pore at an angle of 60–70 degrees. A high-frequency current was applied 1–2 times per lesion for 0.25–0.60 seconds at an intensity of approximately 6–8 W using an electrosurgical apparatus. The average treatment duration was about 45 minutes. In the PDT group, a 5% aminolaevulinic acid (ALA) solution was applied to the face, covered with an occlusive dressing for 90 minutes, and then irradiated with red light-emitting diode light (633 nm) at 100 mW/cm2 and 90 J/cm2 for 15 minutes. Treatments were performed in three consecutive sessions at 2-week intervals, with a follow-up visit 12 weeks after the final treatment. All treatments were administered by the same operator.
Clinical evaluations were conducted by two dermatologists blinded to treatment allocation based on photographs taken before each treatment and at 4 and 12 weeks post-treatment. Acne severity was assessed using individual lesion counts and the IGA score. Treatment success was defined as an improvement of at least two grades (mild, almost clear, or clear) on the IGA score from baseline. Patient satisfaction was measured using a 10-point scale, and pain during treatment was assessed using a visual analog scale (VAS) ranging from 0 to 10.
Statistical analysis was performed using SPSS. Categorical data were compared using the Chi-square test and Fisher’s exact test, while quantitative data were analyzed using the independent samples t-test and Mann–Whitney U test. Repeated-measures ANOVA was used for repetitive measurements. Data were expressed as mean (standard deviation [SD]) or percentage, with a P-value <0.05 considered statistically significant.
Demographic characteristics of the MRF and PDT groups were comparable. Both groups showed significant reductions in inflammatory and non-inflammatory lesions after three treatments. For inflammatory lesions, MRF resulted in a greater mean percentage reduction from baseline compared to PDT after the third session (81% vs. 73%). A significant reduction in inflammatory lesions was observed after the first session in the MRF group and persisted until the end of the study. In contrast, some subjects in the PDT group experienced an increase in inflammatory lesions after the first session due to reactive acne. MRF also led to a significant reduction in non-inflammatory lesions after the second session (55% vs. 44%), but there was no significant difference in lesion improvement between the two regimens after the third session and the final follow-up visit.
Clinical photographs illustrated typical improvements in both groups. Subjects in the MRF group displayed greater improvement, with no pustular eruptions observed during treatment sessions. The IGA success rate was significantly higher in the MRF group at the second and third treatment sessions, with the largest difference observed at the third session (25% superior for PDT). Patient self-assessments of acne improvement generally paralleled the physician’s evaluations, with MRF treatment receiving higher satisfaction scores than PDT during all three treatment sessions.
Regarding adverse events, the MRF group reported significantly lower mean pain scores, erythema, edema, scaling, dryness, and scar formation compared to the PDT group. Post-inflammatory hyperpigmentation (PIH) occurred in 17 patients (42%) in the PDT group and 4 patients (10%) in the MRF group. PIH faded completely after 3–6 months without medical treatment, except for sun protection. Transient acneiform eruptions were observed in 13 patients (32%) in the PDT group and none in the MRF group. No uncontrollable reactions occurred, and no oral hormones or antibiotics were required. Overall, the MRF group experienced fewer adverse events.
Clinical and histopathological studies have demonstrated that MRF can destroy sebaceous glands, reduce inflammatory mediators through radiofrequency thermal damage, and physically disrupt hyperkeratotic plugs in the follicular infundibula via the microneedle. In this study, MRF induced a faster response and a milder complication profile compared to PDT, although the overall degree of improvement was similar at the end of the study. The significant reduction in inflammatory lesions observed after the first session and the absence of sterile pustular eruptions during MRF treatment greatly increased patient satisfaction and compliance with follow-up treatments. Additionally, the PDT group experienced more pain, consistent with previous clinical reports, while MRF was associated with fewer adverse events. This may be attributed to the local motorized needle insertion and motion in MRF, which minimizes epidermal trauma. The severity and course of pigmented lesions were more pronounced in the PDT group, likely due to higher protoporphyrin IX accumulation in both inflammatory lesions and surrounding normal skin. In contrast, MRF delivers electrical current to dermal structures at the desired depth with less epidermal damage, and patients do not need to avoid sun exposure post-treatment, making it suitable for patients with photosensitivity.
MRF therapy also appears more effective at improving acne scars in the later stages of treatment. Various studies have shown the efficacy of RF devices for skin texture improvement, acne scar reduction, and pore size reduction through induced neoelastogenesis and neocollagenesis. The absence of acneiform lesion eruptions in the MRF group is noteworthy, as minimal scars significantly affect patients’ quality of life. Concurrent improvement of acne and scarring through dermal remodeling represents an additional clinical advantage of MRF.
In conclusion, this trial demonstrates the efficacy and safety of MRF and PDT in treating moderate-to-severe acne. Both groups achieved similar clinical improvement, but MRF showed more rapid efficacy and a better safety profile. Therefore, MRF, either as a monotherapy or as part of a combination therapy, represents a viable alternative to PDT for treating moderate-to-severe acne.
doi.org/10.1097/CM9.0000000000002911
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